Alexandre-Emile Beguyer de Chancourtois developed telluric helix periodic table

Alexandre-Emile Beguyer de Chancourtois – organized elements by atomic weights

Category : Personalities
Published by : Data Research Analyst,

Biography & contributions

Alexandre-Emile Beguyer de Chancourtois was a French geologist and mineralogist born on January 20, 1820 – died on November 14, 1886. De Chancourtois was the first to arrange the chemical elements in order of atomic weights.

He devised an early form of periodic table, which he called the telluric helix because the element tellurium came in the middle. It was also somewhat appropriate coming from a geologist as the element tellurium is named after the Earth. de Chancourtois created a fully functioning and unique system of organizing the chemical elements. His proposed classification of elements was based on the newest values of atomic weights obtained by Stanislao Cannizzaro in 1858.

De Chancourtois ordered the elements by increasing atomic weight and with similar elements lined up vertically. A.E.B. de Chancourtois plotted the atomic weights on the surface of a cylinder with a circumference of 16 units, the approximate atomic weight of oxygen. The resulting helical curve, which de Chancourtois called a square circle triangle, brought similar elements onto corresponding points above or below one another on the cylinder. Thus, he suggested that "the properties of the elements are the properties of numbers. He was the first scientist to see the periodicity of elements when they were arranged in order of their atomic weights. He saw that the similar elements occurred at regular atomic weight intervals.

Elements in the same vertical line have atomic weights which differ by 16. For example, lithium's atomic weight is 7, sodium’s is 7 + (16 x 1) = 23 and potassium’s 7 + (16 x 2) = 39.

Mathematically these obey the equation:

atomic weight = 7 + 16n where n is a whole number

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